‘Stellarator’ reactor to be turned on for first time: Strange twisted design could finally make fusion power a reality, say scientists
- Wendelstein 7-X can contain plasma for more than 30 minutes at a time
- It is an alternative to the common donut-shaped Tokamak reactor design
- W7-X reactor claims to be safer and more effective at containing plasma
- Device is currently awaiting regulatory approval for startup in November
Scientists are getting ready to switch on the world's largest 'Stellarator' fusion reactor.
Dubbed Wendelstein 7-X (W7-X), the reactor can continuously contain super-hot plasma for more than 30 minutes at a time.
Researchers claim the unusual design, which is housed in a huge lab in Greifswald, Germany, could finally help make fusion power a reality.
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Scientists are getting ready to switch on the world's largest 'Stellarator' fusion reactor. Dubbed Wendelstein 7-X (W7-X), the reactor can continuously contain super-hot plasma for more than 30 minutes at a time
HOW DOES FUSION POWER WORK?
Fusion involves placing hydrogen atoms under high heat and pressure until they fuse into helium atoms.
When deuterium and tritium nuclei - which can be found in hydrogen - fuse, they form a helium nucleus, a neutron and a lot of energy.
This is down by heating the fuel to temperatures in excess of 150 million°C, forming a hot plasma.
Strong magnetic fields are used to keep the plasma away from the walls so that it doesn't cool down and lost it energy potential.
These are produced by superconducting coils surrounding the vessel, and by an electrical current driven through the plasma.
For energy production. plasma has to be confined for a sufficiently long period for fusion to occur.
Containing super-hot plasma for long periods has been the Holy Grail for reactor designs, and could help scientists provide an inexhaustible source of power.
Fusion reactors, such as the W7-X, work by using two kinds of hydrogen atoms — deuterium and tritium — and injecting that gas into a containment vessel.
Scientist then add energy that removes the electrons from their host atoms, forming what is described as an ion plasma, which releases huge amounts of energy.
Strong magnetic fields are used to keep the plasma away from the walls; these are produced by superconducting coils surrounding the vessel, and by an electrical current driven through the plasma.
The most common design for a reactor is something known as a Tokamak, which is a hollow metal chamber in the shape of a donut.
The fuel is heated to temperatures in excess of 150 million°C, forming a hot plasma.
While the Tokamak design is ideal for containing this plasma, it poses some safety risks, for instance, if the current fails or there's a magnetic disruption.
These disruptions can unleash magnetic forces powerful enough to damage the reactor.
Scientists at the Max Planck Institute say the W7-X is a more practical option and can overcome the safety problems of a Tokamak reactor, according to an in-depth report in Science.
'Tokamak people are waiting to see what happens. There's an excitement around the world about W7-X,' engineer David Anderson of the University of Wisconsin, Madison told Science.
Researchers claim the unusual design, which is housed in a huge lab in Greifswald, Germany, could finally help make fusion power a reality
Pictured is the initial test of the system. The image shows how the fluorescent rod makes closed, nested magnetic surfaces visible
In stellarators, plasma is contained by external magnetic coils which create twisted field lines around the inside of the vacuum chamber
In tokamaks, two sets of magnets are used to contain the plasma; an external set surrounding the vacuum chamber and an internal transformer that drives current in the plasma.
This causes the magnetic field to be stronger in the centre than it is on the outer side.
As a result, plasma contained in a tokamak can moves to the outer walls where it then collapses.
In stellarators, plasma is contained by external magnetic coils which create twisted field lines around the inside of the vacuum chamber, according to Science.
As such, it overcomes can continuously hold the plasma away from the walls of the device.
Its key component is a ring 50 superconducting magnetic coils approximately 3.5 metres in height. In total the device is 16-meters-wide.
The stellarator design was first thought up in 1951 by Lyman Spitzer working at Princeton University.
But at the time, it was thought to be too complex for the constraints of materials available in the middle of the 20th Century.
Now using supercomputers and new materials, researchers believe they can finally make Spitzer's vision a reality.
The photograph on the left combines the tracer of an electron beam on its multiple circulation along a field line through the machine. On the right is one of the interior components of the W7-X being made
While the Tokamak design is ideal for containing this plasma, it poses some safety risks, for instance, if the current fails or there's a magnetic disruption
'We all know the trend of global development, the hunger for energy of emerging economies and emerging countries,' said Professor Johanna Wanka, Federal Minister for Education and Research.
'So when we talk about energy, we need research that keeps all options open. And one of these options is nuclear fusion.
'Wendelstein 7-X is an important step forward allowing us to better evaluate the 'fusion option.'
The machine took 1.1 million hours to assemble, using what has been described as one of the world's most complex engineering models.
Testing of the magnetic field in the Wendelstein 7-X fusion device was completed in June – much sooner than expected.
The test revealed that the magnetic cage for the fusion plasma, which has a temperature of many million degrees, was working as scientists predicted.
The device is currently awaiting regulatory approval for a startup in November.
If the machine works, scientists believe it could herald a change in the direction for fusion power.
ZERO-EMISSION FUSION REACTOR CLAIMS TO BE CHEAPER THAN COAL
A fuel with no greenhouse emissions or radioactive waste that is almost unlimited, sounds too good to be true.
But scientists have taken one more step to make fusion power useful and affordable.
Engineers have designed a concept for a fusion reactor which, when scaled up to the size of a large electrical power plant, would rival costs for a new coal-fired plant with similar electrical output.
Fusion, the process that powers the sun and other stars, entails forging the nuclei of atoms to release energy, as opposed to splitting them, which is fission - the principle behind the atomic bomb and nuclear power.
Engineers from the University of Washington have published their design and analysis findings and will present them at the International Atomic Energy Agency's Fusion Energy Conference in St. Petersburg, Russia, earlie this year.
The design builds on existing technology and creates a magnetic field within a closed space to hold plasma in place long enough for fusion to occur - allowing the hot plasma to react and burn.
The reactor itself would be largely self-sustaining, meaning it would continuously heat the plasma to maintain thermonuclear conditions.
Heat generated from the reactor would heat up a coolant that is used to spin a turbine and generate electricity, similar to how a typical power reactor works.
'Right now, this design has the greatest potential of producing economical fusion power of any current concept,' said Thomas Jarboe, a professor of aeronautics and astronautics at the university.
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